1. Field of the Invention
The present invention relates, generally, to hydraulic couplings and, more specifically, to a hydraulic coupling having a self-adjusting fluid delivery path with anti-rotational capabilities.
2. Description of the Related Art
Hydraulic couplings are well-known devices used in vehicle drive trains. Typically, hydraulic couplings are operatively supported within a housing and are in fluid communication with a source of hydraulic fluid. These devices operate to couple a pair of rotating members, such as drive shafts or axle half shafts about a rotational axis. Thus, hydraulic couplings have been employed as a part of transfer cases that operatively couple the front and rear axles of a vehicle, in limited slip and locking differentials used to couple axle half shafts, as well as other applications commonly known in the art.
Hydraulic couplings of the type known in the related art may include a gear box supported by the housing and that include a gear set designed to allow for relative rotation between the rotary members coupled together by the hydraulic coupling. In addition, these devices also include a coupling mechanism, such as a clutch pack, that operate to lock the rotary members for rotation together. Hydraulic fluid is used to actuate a piston or a like device to engage the clutch and therefore couple the rotating members together. Typically, the gear box is supported for rotation within the housing, but the coupling mechanism is not. Rather, the coupling mechanism may be supported upon one of the rotary members via roller bearings or the like. Nevertheless, because it is supported upon a rotary member and usually adjacent the rotating gear box, and because it acts to couple the rotary members together, the coupling mechanism is subjected to torque during normal operating conditions. When the source of pressurized hydraulic fluid is located outside of the coupling mechanism, for example, it must be delivered through the stationary housing to the coupling mechanism. There are generally two ways to deliver pressurized fluid in these circumstances.
One approach is to use a flexible tube that may be bent or flexed to establish the fluid connection between the outer housing and the coupling mechanism. However, this approach suffers from the disadvantage that there is no “anti-rotation” feature of the tube. Accordingly, where flexible tubing is employed, the hydraulic coupling must also include anti-rotation tabs or special mounting structure that is used to stabilize the coupling mechanism relative to the gear box as well as the outer housing. This necessitates that the coupling mechanism as well as the gear box be assembled in a particular way to align these component parts of the hydraulic coupling in a particular way. This increases the complexity of the hydraulic couplings known in the related art as well as the cost of manufacturing them.
Another approach for delivering pressurized hydraulic fluid to the coupling mechanism is to employ a rigid tube that extends from the outer housing to the coupling mechanism. A rigid tube provides anti-rotational aspects to the system and helps the coupling mechanism resist torque imposed through this system. However, because this approach is also “rigid” all associated apertures and mounting points for the fluid path must be very accurately located. Slight deviations from design in the location of the aperture can create difficulties during the manufacturing process. This increases the cost associated with manufacturing both the housing as well as the coupling mechanism. In addition, it also complicates the assembly of the device.
Thus, there remains a need in the art for a hydraulic coupling having a fluid path that is flexible and self-adjusting such that the corresponding apertures formed in the housing as well as the coupling mechanisms do not have to be located with extreme precision. In addition, there remains a need in the art for a hydraulic coupling having a fluid path that has anti-rotational aspects so as to eliminate the need for anti-rotation tabs or other specific mechanisms used to mount the coupling mechanism to the housing. In addition, there remains a need in the art for a hydraulic coupling having a fluid path that allows for significant misalignment between the interior mounting points and the exterior mounting points for the fluid path.